1. Field of the Invention
This invention relates to the front brake of an electric motor, particularly to one having a simple mechanical structure to effectively control an electric motor and able to save cost.
2. Description of the Prior Art
A conventional electric motor 1 having function of braking and speed reducing, as shown in FIG. 1, is installed with an electromagnetic brake 2 at the rear side to control its shaft to carry out braking. That the electromagnetic brake 2 is installed at the rear side of the conventional electric motor 1 is mainly because the electric motor 1 has its front side provided with a speed-reducing device 3 to lower the speed and heighten the torsion of the output power of the electric motor 1 to let the spindle 4 at the front side of the electric motor 1 able to output a comparatively great power to drive the mechanical equipment connected with it. Under such a condition, after the speed-reducing device 3 carries out speed reduction, the spindle 4 will produce a torsion which is too huge to be braked by the electromagnetic brake 2; therefore the conventional electric motor 1 must have its electromagnetic brake 2 installed at the rear side so as to brake the shaft directly, thus increasing dimensions of the electric motor 1 and taking much space.
The objective of the invention is to offer a front brake of an electric motor, having mechanical structure and connected with an output spindle at the front end of an electric motor, diminishing the dimensions of an electric motor and saving cost and also having no problem involving circuit and electric source in maintenance.
Besides, the electromagnetic brake 2 of the conventional electric motor 1 is supplied with direct current for carrying out operation, but for the present almost all the factories and families are supplied with alternating current for use; therefore the electromagnetic brake 2 has to be additionally provided inside with a rectifier to convert alternating current into direct current and a control circuit, thus complicating its structure and increasing cost.